My ignorance of the speculations of the meta -language brigade is almost total, Max. But from a limited study of vocal tract mechanics and early language formation I would observe it starts as the simplest full-throat sound (similar to why a baby's early sounds will often include /a/ in such vowel&consonant clusters as dadadadad, mamamamama), modified by the natural diphthong effect of closing the lips and retracting the tongue at the end of the production.

There might be some universal tendencies, but I think you'd be hard pressed to distinguish them from chance. An open-mouthed vocable of surprise (of the ah/oh kind), a slack one of assent (ha/hm/mm), and a broken one of negation (uh-uh/mm-mm) perhaps occur more widely than can be explained as common culture. For example, glottalized m-m means 'no' in Hausa.

But really, you've got quite as many counterexamples: iie in Japanese for 'no', Greek ne 'yes'. These mama effects are pretty weak.

English aye 'yes' is of unknown origin, with no obvious counterpart even in German or Norse. Japanese hai points to Old Japanese pai or some such, but H < P anyway. For the Maaori, you'd want to get any other Austronesian cognates first to see what it came from.

There's no way any of those groups can be connected. It's been suggested that Japanese and Austronesian are related, but if so it's at such a great depth that no single word can be held up as cognate; and there hasn't been any opportunity of borrowing in millennia either.

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